In Aluminium Extruded profiles 6063.T4, its hardness was increased keeping 3 to 4 months in open?

Yes，6063 T4 aluminum extrusion profile hardness can be increased if it was kept 3-4 months in the open air.

After aluminum extrusion process, 6063 aluminum profile was naturally placed for a certain period of time at room temperature, the strength and hardness of 6063T4 will be increased, which is called as natural aging. 6063 T4 can be used for the bending process in the production.

Keep 6063 aluminum profile at a certain temperature higher than room temperature for a certain period of time to improve the strength and hardness of the aluminum alloy. The method is called the artificial aging, 6063 T5 and T6 will be aged in the aging furnace for hardness.

The aging hardening process is a process of decomposition and precipitation of supersaturated solid solution. This process can be divided into three stages during the whole stage of aging:

The first stage is the enrichment of solute atoms along a certain crystal plane of the substrate to form concentration segregation, namely GP zone In this stage, the GP zone is coherent with the parent phase, the surface energy between the structure and the parent phase is small, and the strength and hardness of the aluminum profile begin to increase;

In the second stage, the GP zone grows up and transforms into an intermediate phase (θ’); The θ’ phase is completely co-lattice with the substrate and is evenly distributed in the substrate; however, the structure of the θ’ phase is different from that of the substrate. Large lattice distortions will occur around the phase, resulting in a significant strengthening of the aluminum profile. The strengthening effect is greater than that of the GP zone;

The third stage is the transition of the intermediate transition phase (θ’) into a stable phase with an independent crystal structure. The strength and hardness of the aluminum profile begin to decrease, which is the beginning of over aging; if the aging time is extended Or the temperature rises, the equilibrium phase θ gathers and grows, the aluminum profile will be over-aged, and the strength and hardness of the over-aged aluminum profile will be significantly reduced;

The aging hardening ability of aluminum profiles is related to the concentration of the solid solution and the aging temperature. Theoretically, the higher the concentration of the solid solution, the stronger the aging effect. The aluminum profile close to the limit solubility has the greatest strengthening effect; on the contrary, the lower the effect.

1.Lowering the aging temperature can hinder or inhibit the aging hardening effect (for example, at -18°C);
2.Increasing the aging temperature will speed up the aging hardening speed and shorten the aging time, but the softening speed of the hardening peak will also be faster;
3. In the temperature range with peak intensity, the highest intensity value decreases with the increase of the effective temperature;
4.In artificial aging, the strength will peak. When the strength of the aluminum profile reaches the highest value, if the aging time is continued to be extended, the strength will not increase, but will start to decrease, resulting in "over-aging";
5 Natural aging will not have over-aging;

For 6063 aluminum profiles, when natural aging is applied, the yield strength is slightly lower, but the corrosion resistance is better; when artificial aging is applied, the yield strength of aluminum profiles is higher, but the elongation and corrosion resistance will be reduced.